Sealed electrical terminals



Q a v I m m M m5 R Z mm m K v w. T a F? W Z W aw Feb. 17, 1959 R. BOWERS ETAL SEALED ELECTRICAL TERMINALS Filed Sept. 17, 1953 United States Patent SEALED ELECTRICAL TERMINALS Roy L. Bowers and Gerald W. Colby, Flint, Mich., as-

signors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 17, 1953, Serial No. 380,694

1 Claim. (Cl. 174-77) This invention relates to electrical terminals and more particularly to sealed electrical terminals for providing insulated leads through walls of containers, casings or housings. I

it is often desirable to provide electrically operated apparatus such as motors or heaters within containers and to which apparatus electrical energy must be conducted by leads passing through the walls of the containers. The lead-in connections in many cases must be tightly sealed against leakage of fluid from or into the container and usually must be well insulated from the container walls. Solely by way of example, such an instance is that of a pump and motor installed within a tank as illustrated in United States Letters Patent No. 2,260,946 granted October 28, 1941 in the names of Alfred C. Korte and Kenneth Lannert.

Lead-in terminals or bushings as heretofore used and particularly in the case of tanks on vehicles are a frequent source of difliculty due to the fact that vibrations and/ or changes in temperature place considerable strain upon the seal and fluid leakage ultimately occurs.

One of the objects of the present invention is to provide an electrical terminal of improved construction which will eifect a reliable seal against the passage of fluid when mounted on a container and which is not subject to deterioration due to changes in temperature or by the effect of vibration.

Another object is to provide an improved terminal having a minimum number of parts which may be easily assembled into a complete unit that is simple in construction and extremely eifective as a seal against the passage of fluids regardless of whether such fluids be in the liquid, vapor or gas form.

A feature of the invention resides in a plug of rubberlike material distorted in a concentrated area against a shoulder of a casing to form a seal against the passage of fluid in any direction.

Another feature of the invention is a terminal casing with a restricted passage having a rubber plug inserted therein and the plug being distorted and clamped in position by means of current conducting means insulated from the casing by a dielectric member and the plug.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

Figure 1 is a sectional view through the top of a tank and a longitudinal section through an electrical terminal fixed thereto and in which the present invention is embodied;

Figure 2 is an exploded sectional view of some of the parts shown in Figure 1;

Figure 3 is a section taken along the line 33 of Figure 1; and I Figure 4 is a section taken along the line 44 of Figure 1.

In Figure 1 a tank is shown having a top 12 and 2,874,206 Patented Feb. 17, 1959 a reinforcement or angle bar 14 surrounding the tank and serving as a means for attaching the tank and top together. The top 12 is provided with an opening 18 through which the electrical terminal of the present invention is arranged to conduct energy for operating a motor (not shown) enclosed within the tank.

The terminal comprises a casing generally indicated at 20 and which is flanged at 21 partially around one side or the bottom thereof and an end portion 22 of the casing is rectangular in cross-section as seen in Figure 4. Another longitudinal end portion 23 of the casing has a halfcylindrical top as seen in Figure 3 and an intermediate portion 24 of the casing 20 is reduced somewhat in overall cross sectional size. A gasket 26 is interposed between the tank top 12 and the casing 20 at the margins of the opening 18. Bolts 19 (only one shown, see Figure 4) are employed to hold the casing 20, gasket 26 and tank top 12 in sealed relation. A passage comprising intersecting branches is formed in the casing 20 and this passage comprises a chamber 27 of rectangular crosssectional configuration within the end portion 22. This chamber communicates with two axially aligned cylindrical chambers 28 and 29 located within the casing portions 24 and 23 respectively. -As the chamber 28 is smaller in diameter than the chamber 29, an annular ridge is formed between the chambers 27 and 29 presenting oppositely facing shoulders 30 and 31.

Itwill be noted that the shoulder 30 lies in a plane normal to the tank top 12 whereas the shoulder 31 is conical except for an inner annual portion 32 thereof which is normal to the tank top.

The chamber 29 of the right-angled passage terminates with the shoulder portion 32 and a cylindrical plug 34 of rubber-like material is provided the diameter thereof being such as to lit in slidable relation within the chamber 29. One end of the plug 34 is reduced as at 36 to fit within the restricted portion of the passage or intermediate chamber 28 of the casing 20 and a shoulder 38 is formed on the rubber plug which shoulder, while undistorted as shown in Figure 2, is conical and which is formed at an angle of approximately 45 with the axis of the plug thereby conforming with the conical portion of the shoulder 31 which is also made at an angle of 45. It is particularly to be noted that the annular shoulder portion 32 of the casing 20 does not conform with the shoulder 38 on the plug unless the rubber material be forced to conform and thereby be locally placed under stress and distorted. The concentration of compression force exerted by the relatively unyielding shoulder portion 32 upon the plug causes the latter to be distorted as seen in Figure l. The plug is made hollow as at 40 and is provided with an end opening 42 through which a metallic terminal pin 44 may be inserted during assembly of the unit and through which opening a conductor cable may ultimately be inserted in completing the required circuit. The pin 44 passes through the reduced portion 36 of the plug and is adapted to be placed under tension to bring about the plug distortion with the aid of other parts now to be described.

A washer 46 with a rolled edge 48 is interposed between a hexagonal portion 50 made integral with the pin 44 and the reduced portion of the rubber-like plug 34. Advantageously a second and smaller washer 52 is interposed between and in contact with the washer 46 and the hexagonal portion 50 and this aids in the assembly operation. It will be noted that the outside diameter of the washer 46 is slightly greater than that of the chamber 28 and intermediate the inner and outer diameters of the shoulder 31 in order to increase resistance of the plug material against shear. One end of the pin 44 adjacent and extending from the hexagonal portion 50 is so formed as to constitute a head 54 over which a lead wire conveniently may be secured.

A dielectric member 56 of rectangular configuration and placed within The chamber 27 is arranged with one surface in a plane parallel with the shoulder 30 and is drilled as at'58 freely to receive a threaded end of the pin. 44. The dielectric member may be composed of Bakelite or some other rigid and strong material and this member is provided with a U-shaped ridge 60, the open end of which is directed downwardly as seen in Figure 4.

A terminal plate 62 is riveted as at 64 to the dielectric member 56 and extends downwardly from within the ridge 60. It will be noted that the rivet 64 is out of contact with the casing 20 and that this is assured by a dielectric paper insulator 65 interposed between the member 56 and the shoulder 30. The terminal plate 62 is provided with a hub 66 which is internally threaded to receive the threads of the pin 44. The lower end of the terminal plate 62 is provided with two loop portions or ferrules 68 and 70, the ferrule 70 being adapted tightly to restrain in position the end of an insulated cable 72 clear of the sides of the opening 18. The conductor portion 74 of the cable 72 is tightly held by the loop or ferrule 68.

In constructing or assembling the terminal unit the rubber-like plug 34 is inserted into the casing 20 and the threaded end ofthe pin 44, with the washers 46 and 52 thereon, is pushed through the rubber plug, the paper insulator 65 and the dielectric member 56 and placed into threaded engagement with the terminal plate 62. Rotation of the pin 44 by means of the hexagonal portion 50 will cause the rubber plug and the dielectric member 56 to be clamped into tight relation with the shoulders 31 and 30 of the casing 20 and effect distortion of the plug and the desired seal against fluid leakage.

After assembly of the unit, including the attachment of the cable 72, bolts 19 are used firmly to locate the terminal unit with respect to the tank so that no possibility of fluid leakage from or into the tank 10 exists.

It should be noted that the reduced portion 36 of the rubber-like plug is of such axial length as to contact the paper insulator 65 when assembly is complete as shown in Figure 1. This construction is preferred but is not essential in practicing the present invention as a clearance between the plug and the insulator may be embodied in the design. The insulator 65 is not essential if adequate clearance is left between the rivet and the shoulder 30 but its presence is preferred.

The forms of the metallic casing 20 and the hollow rubber-like plug 34 are such that not only is a reliable seal effected but a connection to the head 54 of the pin 44 is protected or'guarded against inadvertent displacement.

Having described our invention, what we claim as new and desire to secure by Letters Patent of the United States An electrical terminal comprising an integral one-piece relatively hard casing having an externally disposed mounting flange and defining a passage leading through the casing as two branches intersecting at an angle, the material of said casing forming an internal annular ridge restricting one of said branches and having oppositely facing hard shoulders, a plug of relatively soft rubberlike material extending into said one branch with one end thereof extending into the Zone between said shoulders, dielectric means in the other of said branches and contacting one of said shoulders as an insulator, an annular and relatively soft shoulder on said plug facing the other of said shoulders, said two last-mentioned shoulders having dissimilar surface configurations, conducting means passing through said plug and dielectric means, and a portion of said conducting means between said shoulders being under tension to deform said soft shoulder and seal the same against said other shoulder and to maintain said seal.

References Cited in the file of this patent UNITED STATES PATENTS 1,768,522 Brown June 24, 1930 2,328,111 Thornbery Aug. 31, 1943 2,563,829 Fitzgerald et al. Aug. 14, 1951 2,603,682 Uline et al. July 15, 1952 2,610,222 Burtt et al. Sept. 9, 1952 FOREIGN PATENTS 1,011,629 I France June 25, 1952 679,410 Great Britain Sept. 17, 1952 

